I used to work in a leather goods factory in Tyneside, Englandicon

Part of the stores had shelves of the flat sling ends with the metal prongs....and boxes of the correct hollow rivets. Elsewhere in the store were rolls of the 1" cotton webbing.

The company did a lot of export orders for the Middle East Arab states & IIRC the slings were occasionally sent there, but not that often.

When I looked into making L42 slings about 4 or 5 years ago I found approx. 3 British webbing suppliers that still produced the 1" cotton rifle sling webbing

...may have some remnants of sling parts & fittings, etc. from the Tyneside factory: as I bought all their stable belt webbing when they went into liquidation - must have about 40/50 rolls of stable belt cotton web!!